It’s also possible that using the NX-01’s and NX-02’s construction times as a model would be misleading in an emergency scenario where United Earth diverted resources to bang out ships as fast as possible.
If we’re going with similarities to real world naval construction, fhe Enterprise and Columbia are ostensibly prototypes and testbeds. The lessons learned putting them together would be used to streamline the process to where Starfleet could crank out NX starships at a faster rate, and getting them space worthy would be the priority and tweaking any systems during shakedown could be achieved after the fact.
For example, the Essex Class aircraft carrier during World War II. The US Navy was able to significantly chop the construction time from the early ships of the class to the later ones.
If you consider the
Essex class to be similar to the NX class, then the
Kaiser class escort carriers would be comparable to the
Daedalus.
The NX class is a complex top of the line ship, much like the
Essex class, meaning relatively few will be built.
Twenty-four
Essex class carriers were built during the war. Five were already under construction when Japan attacked Pearl Harbor, six on order and two more were ordered in the days after the attack
In the case of the
Kaiser class escort carrier, fifty of the carriers were ordered with the lead ship of the class,
Casablanca, beings delivered on July 8, 1943, and the fiftieth
Munda, being delivered exactly one year later, July 8, 1944, thanks in part to round the clock construction and the relatively plain design.
In the month following Peal Harbor, the US Navy placed orders for 298 surface warships, almost all of them destroyers and destroyer escorts.
In the month following the Battle of Midway, June 4, 1942, the United States had a grand total of 131 aircraft carriers of all types in various stages of construction, conversion, or on order.
1 Large Carrier (Midway)
22 Fleet Carriers (Essex)
9 Light Carriers (Independence)
99 Escort Carriers, 34 of which would be transferred to Great Britian upon completion.